1. Field Of The Invention
The invention herein pertains to certain bridge supporting structures, and particularly to "short span" highway bridge structures for spans which are generally eighty feet or less.
2. Description Of The Prior Art And Objectives Of The Invention
It has been estimated that as many as two hundred thousand of this nation's highway bridges are deficient and must be replaced or substantially repaired in the near future. Many of the bridges which are deficient are of the "short span" type, i.e., are less than eighty feet in length generally used by motor vehicles on secondary roads and highways. The supporting structure of these short span secondary highway bridges may be either longitudinal concrete or steel girders, positioned parallel to the centerline of the roadway which provide the primary strength and load support across the span. Steel girders usually require supplemental lateral restraints for lateral rigidity which under conventional bridge constructions involves steel cross bracing between the girders. However, conventional bridge constructions which utilize steel girders have bolt holes therein or welded clips thereto required for connecting the lateral bracing to the girders and for the attachment of the supports for the guard rails on each side of the bridge. Such bridges generally have concrete decking, however bridges with steel girders often use treated timber decking which is an established, economical and proven bridge deck comparing favorably on ability to withstand freezing weather and salting operations. Such bridges have proved uneconomical to manufacture and install and are often insufficient in long term guardrail rigidity. Conventional bridge construction is also expensive and labor intensive, and in some instances has prohibited local governments from repairing or replacing bridges until they are dangerously decrepit.
It is therefore an objective of the present invention to provide a bridge structure and design which has components that can be easily fabricated by relatively unskilled workers and which can be delivered to the job site for assembly and installation with ease and convenience.
It is another objective of the present invention to provide a bridge structure in which the principal components for lateral bracing are standardized and can be utilized in any width, skew or span of bridge and which may be mass produced and warehoused for economy purposes.
It is also another objective of the present invention to provide a bridge structure easily adaptable to any skew or angle of the span crossing with minimum engineering or fabrication required.
It is still another objective of the present invention to provide the lateral bracing for a girder bridge structure whereby each lateral brace consists of a pair of steel members, one above and the other below the girders, and each steel member is continuous across the width of the bridge.
It is another objective of the present invention to provide a bridge structure which utilizes a relatively small number of components yet which will provide the stability and rigidity for all state and federal requirements.
It is yet another objective of the present invention to provide a bridge structure whereby the lateral braces are securely affixed at each girder without penetrating the girder or welding thereto.
Various other objectives and advantages of the present invention will become apparent to those skilled in the art as a more detailed presentation is set forth below.